Tejun Heo e58126f570 writeback: fix possible underflow in write bandwidth calculation ... commit c72efb658f upstream. From 1ebf33901ecc75d9496862dceb1ef0377980587c Mon Sep 17 00:00:00 2001 From: Tejun Heo <tj@kernel.org> Date: Mon, 23 Mar 2015 00:08:19 -0400 2f800fbd77 ("writeback: fix dirtied pages accounting on redirty") introduced account_page_redirty() which reverts stat updates for a redirtied page, making BDI_DIRTIED no longer monotonically increasing. bdi_update_write_bandwidth() uses the delta in BDI_DIRTIED as the basis for bandwidth calculation. While unlikely, since the above patch, the newer value may be lower than the recorded past value and underflow the bandwidth calculation leading to a wild result. Fix it by subtracing min of the old and new values when calculating delta. AFAIK, there hasn't been any report of it happening but the resulting erratic behavior would be non-critical and temporary, so it's possible that the issue is happening without being reported. The risk of the fix is very low, so tagged for -stable. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> Fixes: 2f800fbd77 ("writeback: fix dirtied pages accounting on redirty") Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2015-04-19 10:10:48 +02:00
..
backing-dev.c	bdi: avoid oops on device removal	2014-04-26 17:15:35 -07:00
balloon_compaction.c
bootmem.c	mm: Add alloc_bootmem_low_pages_nopanic()	2013-01-29 19:32:59 -08:00
bounce.c	mm/bounce.c: fix a regression where MS_SNAP_STABLE (stable pages snapshotting) was ignored	2013-10-13 16:08:33 -07:00
cleancache.c	mm: cleancache: clean up cleancache_enabled	2013-04-30 17:04:01 -07:00
compaction.c	mm/compaction: fix wrong order check in compact_finished()	2015-03-18 13:22:28 +01:00
debug-pagealloc.c
dmapool.c
fadvise.c	teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long	2013-03-03 22:46:22 -05:00
failslab.c
filemap_xip.c	lift sb_start_write() out of ->write()	2013-04-09 14:12:56 -04:00
filemap.c	mm: memcg: handle non-error OOM situations more gracefully	2014-11-21 09:22:56 -08:00
fremap.c	mm: fix use-after-free in sys_remap_file_pages	2014-01-09 12:24:24 -08:00
frontswap.c	mm: frontswap: invalidate expired data on a dup-store failure	2014-12-16 09:09:41 -08:00
highmem.c	Some nice cleanups, and even a patch my wife did as a "live" demo for	2012-12-20 08:37:05 -08:00
huge_memory.c	mm: numa: Do not mark PTEs pte_numa when splitting huge pages	2014-10-09 12:18:42 -07:00
hugetlb_cgroup.c	mm/hugetlb: create hugetlb cgroup file in hugetlb_init	2012-12-18 15:02:15 -08:00
hugetlb.c	mm/hugetlb: add migration entry check in __unmap_hugepage_range	2015-03-18 13:22:27 +01:00
hwpoison-inject.c
init-mm.c
internal.h	mm: accelerate munlock() treatment of THP pages	2013-02-27 19:10:09 -08:00
interval_tree.c
Kconfig	mmKconfig: add an option to disable bounce	2013-04-29 15:54:40 -07:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c	hlist: drop the node parameter from iterators	2013-02-27 19:10:24 -08:00
ksm.c	mm: close PageTail race	2014-04-03 12:01:05 -07:00
maccess.c
madvise.c	mm: madvise: complete input validation before taking lock	2013-04-29 15:54:37 -07:00
Makefile	memcg: add memory.pressure_level events	2013-04-29 15:54:38 -07:00
memblock.c	memblock: fix missing comment of memblock_insert_region()	2013-04-29 15:54:38 -07:00
memcontrol.c	mm: memcg: handle non-error OOM situations more gracefully	2014-11-21 09:22:56 -08:00
memory_hotplug.c	mm/memory hotplug: postpone the reset of obsolete pgdat	2015-04-19 10:10:47 +02:00
memory-failure.c	mm/memory-failure.c: don't let collect_procs() skip over processes for MF_ACTION_REQUIRED	2014-06-30 20:09:42 -07:00
memory.c	mm/memory.c: actually remap enough memory	2015-03-18 13:22:28 +01:00
mempolicy.c	cpuset,mempolicy: fix sleeping function called from invalid context	2014-07-17 15:58:00 -07:00
mempool.c
migrate.c	mm: numa: avoid unnecessary work on the failure path	2014-01-09 12:24:23 -08:00
mincore.c	swap: make each swap partition have one address_space	2013-02-23 17:50:17 -08:00
mlock.c	mm: try_to_unmap_cluster() should lock_page() before mlocking	2014-05-06 07:55:32 -07:00
mm_init.c	mm: init: report on last-nid information stored in page->flags	2013-02-23 17:50:18 -08:00
mmap.c	mm/mmap.c: fix arithmetic overflow in __vm_enough_memory()	2015-03-18 13:22:27 +01:00
mmu_context.c	mm: remove old aio use_mm() comment	2013-05-07 18:38:27 -07:00
mmu_notifier.c	mm: mmu_notifier: re-fix freed page still mapped in secondary MMU	2013-05-24 16:22:51 -07:00
mmzone.c	mm: rename page struct field helpers	2013-02-23 17:50:18 -08:00
mprotect.c	mm: fix TLB flush race between migration, and change_protection_range	2014-01-09 12:24:23 -08:00
mremap.c	mm, thp: close race between mremap() and split_huge_page()	2014-06-07 13:25:31 -07:00
msync.c
nobootmem.c	mm, nobootmem: do memset() after memblock_reserve()	2013-04-29 15:54:39 -07:00
nommu.c	mm/nommu.c: fix arithmetic overflow in __vm_enough_memory()	2015-03-18 13:22:28 +01:00
oom_kill.c	mm: memcg: handle non-error OOM situations more gracefully	2014-11-21 09:22:56 -08:00
page_alloc.c	OOM, PM: OOM killed task shouldn't escape PM suspend	2014-11-14 08:47:58 -08:00
page_cgroup.c	cgroup/kmemleak: add kmemleak_free() for cgroup deallocations.	2014-11-14 08:47:59 -08:00
page_io.c	Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block	2013-05-08 10:13:35 -07:00
page_isolation.c	mm: fix zone_watermark_ok_safe() accounting of isolated pages	2013-01-04 16:11:46 -08:00
page-writeback.c	writeback: fix possible underflow in write bandwidth calculation	2015-04-19 10:10:48 +02:00
pagewalk.c	mm: pagewalk: call pte_hole() for VM_PFNMAP during walk_page_range	2015-02-11 14:48:16 +08:00
percpu-km.c
percpu-vm.c	percpu: perform tlb flush after pcpu_map_pages() failure	2014-10-05 14:54:13 -07:00
percpu.c	Revert "percpu: free percpu allocation info for uniprocessor system"	2014-11-14 08:47:53 -08:00
pgtable-generic.c	mm: fix TLB flush race between migration, and change_protection_range	2014-01-09 12:24:23 -08:00
process_vm_access.c	Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys	2013-03-12 11:05:45 -07:00
quicklist.c
readahead.c	teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long	2013-03-03 22:46:22 -05:00
rmap.c	mm: fix sleeping function warning from __put_anon_vma	2014-06-30 20:09:42 -07:00
shmem.c	shmem: fix nlink for rename overwrite directory	2014-10-05 14:54:11 -07:00
slab_common.c	slab_common: fix the check for duplicate slab names	2014-07-31 12:53:50 -07:00
slab.c	slab: fix init_lock_keys	2013-07-21 18:21:26 -07:00
slab.h	memcg: check that kmem_cache has memcg_params before accessing it	2013-09-07 22:09:58 -07:00
slob.c	mm: rename page struct field helpers	2013-02-23 17:50:18 -08:00
slub.c	slub: Fix calculation of cpu slabs	2014-02-13 13:48:00 -08:00
sparse-vmemmap.c	sparse-vmemmap: specify vmemmap population range in bytes	2013-04-29 15:54:35 -07:00
sparse.c	mm, hotplug: avoid compiling memory hotremove functions when disabled	2013-04-29 15:54:37 -07:00
swap_state.c	swap: avoid read_swap_cache_async() race to deadlock while waiting on discard I/O completion	2013-06-12 16:29:45 -07:00
swap.c	mm: close PageTail race	2014-04-03 12:01:05 -07:00
swapfile.c	frontswap: fix incorrect zeroing and allocation size for frontswap_map	2013-06-12 16:29:46 -07:00
truncate.c	mm: Remove false WARN_ON from pagecache_isize_extended()	2014-11-14 08:48:00 -08:00
util.c	vm_is_stack: use for_each_thread() rather then buggy while_each_thread()	2014-10-05 14:54:16 -07:00
vmalloc.c	mm/vmalloc.c: fix an overflow bug in alloc_vmap_area()	2013-11-13 12:05:34 +09:00
vmpressure.c	memcg: add memory.pressure_level events	2013-04-29 15:54:38 -07:00
vmscan.c	mm, vmscan: prevent kswapd livelock due to pfmemalloc-throttled process being killed	2015-01-16 06:59:03 -08:00
vmstat.c	mm: numa: return the number of base pages altered by protection changes	2013-12-08 07:29:27 -08:00